Absorption spectra Bohr atom

However, in the sodium atom, An = 0 is also allowed. Thus the 3s —> 3p transition is allowed, although the 3s —> 4s is forbidden, since in this case A/ = 0 and is forbidden. Taken together, the Bohr model of quantized electron orbitals, the selection rules, and the relationship between wavelength and energy derived from particle-wave duality are sufficient to explain the major features of the emission spectra of all elements. For the heavier elements in the periodic table, the absorption and emission spectra can be extremely complicated - manganese and iron, for example, have about 4600 lines in the visible and UV region of the spectrum. 

The concept of quantized energy applies to phenomena related to the emission of light as well as to the absorption of light. In this, it will serve in the interpretation of the hydrogen emission spectrum, leading Bohr to formulate his description of the hydrogen atom, the third phase in the formation of quantum theory. 

Analysis of the spectrum of the H atom led to the Bohr model, the first step toward our current model of the atom. From its use by 19 -century chemists as a means of identifying elements and compounds, spectrometry has developed into a major tool of modem chemistry. The terms spectmscopy, spectrophotometry, and spectrometry refer to a large group of instrumental techniques that obtain spectra that correspond to a substance s atontic or molecular eneigy levels. (Elements produce lines, but complex molecules produce spectral peaks.) The two types of spectra most often obtained are emission and absorption spectra ... 

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